When an invasive, non-native plant from Brazil turned up in Ross Barnett Reservoir in recent years, managers of local waterways took notice. When it was confirmed present in Pickwick Lake though, it was time to take serious action. Today, fisheries biologists and boaters alike should be on the lookout for a plant that can take over a lake or pond and smother it in short order.
Giant salvinia is a tropical plant native to Brazil. Exactly how far north it can survive and thrive is not known, but if it gets established in Pickwick Lake, it can certainly menace any lakes and rivers south of Tennessee.
Giant salvinia is known to be present in the Aberdeen, Columbus and Aliceville Lakes of the Tenn-Tom Waterway. Those waters are managed by the U.S. Army Corps of Engineers, and their plant management biologists have been spraying to combat it, to some success.
“They’re seeing less and less of it on Columbus Lake,” said Bryant Haley, a fisheries biologist with the Mississippi Department of Wildlife, Fisheries and Parks.
It is thought barge traffic has been involved in its spread. As yet, it has not been confirmed in any state lakes, though officials are on the constant lookout.
“We’re trying to keep it from spreading from where it already is to somewhere new,” said Dustin Rodgers, a fisheries biologist and area supervisor with the MDWFP. “We don’t know of any on any state lakes. If there were, we’d go out immediately and spray. If you see any, please let us know immediately.”
The plant was first brought to the United States for ornamental purposes in aquariums and backyard rock and water gardens. It escaped in the Houston, Texas area in the 1960s and has since run amuck in many waterways along the Louisiana-Texas line. In Lake Sam Rayburn, a tremendous reservoir in eastern Texas, the plant has completely taken over coves and backwaters that are, on their own, larger than Ross Barnett Reservoir. The plant thrives in warm, damp climates and can be an explosively-growing problem that demands constant attention. How much attention how far north is a question to be answered.
Under ideal conditions, such as a typical Mississippi summer, a mat of giant salvinia can double its biomass in 36 hours. A piece the size of a fingertip, brought in unintentionally from another lake on a boat or trailer, can turn into a colony, then a patch the size of an office desk, then the size of a suburban home, then a city block, then a neighborhood in very little time.
The plant is not cold-tolerant and a hard freeze, such as the one this area experienced for a few days last winter, will kill it. That said, it grows in thick mats and can double and redouble its size so quickly, even a single summer’s growth can be enough to wreak major havoc. Left unchecked, it can quickly overwhelm whole bodies of water, consuming nutrients and blocking out sunlight, eventually rendering areas useless for any form of recreation.
Waterway managers routinely spray infestations of other plants, native and otherwise, and giant salvinia can be controlled by spraying. The difference with it is, it grows so quickly, jumping on it immediately is a vital step to controlling it. Officials ask boaters to be especially mindful of what may stick to their trailers when loading or unloading a boat in waters affected by the plant. Even a small chunk of the weed can be enough to get a brand new infestation going.
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